Elevator for passengers and freight



(No Model.)

W. W. RENWIGK. ELEVATOR FOR PASSENGERS AND FREIGHT.

No. 495,616. Patented Apr. 18, 1893.

Mmwm Jnwmht v UNITED STATES PATENT OFFICE.

WVILLIAM WHETTEN RENWICK, OF MILLBURN, NEW JERSEY.

ELEVATOR FOR PASSENGERS AND FREIGHT.

y@PEGIFICATION forming part of Letters Patent No. 495,616, dated April18, 1893.

Application filed September 8, 1892. Serial No. 445,355. (No model.)

.To aZZ whom it may concern:

Be it known that I, WILLIAM WHETTEN RENWIOK, of Millburn, in the countyof Essex and State of New Jersey, have made a new and useful inventionof an Improvement in Elevators for Passengers and Freight; and I dohereby declare that the following, in connection with the accompanyingdrawings, is a full, clear, and exact description and specification ofthe same.

My invention has reference to the means of counterpoising the weight ofthe elevator car in that class of hydraulic elevators in which asingleacting pressure cylinder is used. The weight of the car (and itsappurtenances) of elevators has heretofore been counterbalanced t0 therequired extent by a counterpoise weight connected with the car by ropesextended over pulleys so that the counterpoise weight moves in thereverse direction to that of the car. When the force operating theelevator is water acting in a cylinder under the pressure of compressedair, this system of counterbalancing the weight is attended with thedefect that the momentum of the counterpoise weight tends to cause it tocontinue its movement after the supply valve of the hydraulic elevatorcylinder is closed, and consequently the elevator car totters orvibrates on such occasions.

The object of the present invention is to enable a moving counterpoiseweight and its attendant momentum to be dispensed with, and it consistsof a certain combination of devices by which the Weight of the elevatorcar of an elevator operated by Water under the pressure of compressedair in a closed supply tank is counterbalanced in whole or in part bysubjecting the Water discharging from the elevator cylinder into aclosed discharge tank to the pressure of air in the latter reduced belowthat in the supply tank by the operation of a reducing valve. The saidcombination is recited in the claim at the close of this specification.

In order that the said invention may be fully understood, I haverepresented in the accompanying drawings and will proceed to describethe best form of apparatus which I have thus far devised for practicingthe invention; it being understood that the apparatus may be modified ascircumstances or the views of users or makers may render expedient.

.In the said drawings, Figure 1 represents a side elevation of the saidapparatus without the elevator car and the greater portions of theconnecting ropes. Fig. 2 represents upon a smaller scale the elevatorcar and sufficient portions of the connecting ropes and pulleys toenable their operation to be understood.

The elevator car, A, may be of any desirable construction and may beguided by guides in the usual manner. It is connected by means of thehoisting ropes, b (one or more), with the piston rod, 0, of the hoistingpiston of the hydraulic cylinder D, which Iprefer to be arrangdhorizontally; the said hoisting ropes being conducted over the travelingpulleys, E, and the fixed pulleys, F, in the usual manner common withsuch elevators so as to multiply the extent of movement of the piston.The weight of the traveling pulleys Ewhe'n arranged to move horizontallymaybe supported in the usual Way by Wheels running upon guides, asillustrated in the drawings; there being one guidef, and one carryingwheel g, at each side of the gangof pulleys. The hydraulic cylinder, D,is a single acting one; that is to say the water under pressure issupplied to one side only of the piston in said cylinder, and isdischarged from the same side of the piston into a discharge tankwithout acting upon the opposite side of said piston. The water, bywhich the piston of the hydraulic cylinder, D, is operated, is deliveredfrom a pressure supply tank, H, by means of a pipe, m to the valvechest, I, of the cylinder, and passes thence to the pressure side of thepiston by the pipe or. The pressure tank is preferably a closed 011e, H,in which the requisite pressure is obtained by compressed air. Thedelivery of water to the cylinder and its discharge therefrom areregulated by a valve working in the said valve chest I. This valve andthe valve port may be of the usual piston variety used with singleacting elevator cylinders, and as such valves are Well known to makersof elevators it is not deemed necessary to describe and represent one indetail. The pressure supply tank, H, is supplied with water by means ofan ordinary steam pump J; and the Water in said pressure supply tank issubjected to the pressure of air compressed therein, some one of thecustomary provisions for making good the leakage of air from thepressure tank of the elevator being used. The cylinder valve forsupplying and discharging the water may be operated from the car, A,inthe usual manner by means ofahand rope, 70, connected with the valveoperating shaft by apulley l. The apparatus thus far described issubstantially the same as elevator apparatuses in common use with singleacting hydraulic cylinders supplied with water under the pressure ofcompressed air.

The valve chest is connected by a pipe, w, with the discharge tank M,which, instead of beingin open connection with the atmosphere, is closedso as to contain compressed air which exerts pressure upon thedischarging water when the valveis moved to the position for dischargingthe water from the cylinder, and thus causes the discharging water toexert pressure upon the piston during the descent of the I ed with theupper part of the closed pressure supply tank, H, by means of aconnecting pipe, P, and an automatic reducing valve, Q, of any of theordinary constructions employed to reduce the pressure of steam flowingfrom a high pressure to a lower one; and as such reducing valves arewell known as common articles of trade, it is not deemed necessary todescribe and represent one in detail. This construction enables thepressure of the air in the closed pressure discharge tank to bemaintained automatically notwithstanding leakage, and without theemployment of a special air forcing pump for such purpose. I prefer toapply to the closed pressure discharge tank an ordinary safety valve soas to prevent excess of pressure therein; and the safety valve may beconnected, as at r, with the tank connecting pipe P. I also prefer toapply water gages, s, s, to the closed tanks, and to insert stop valves,25, t, in the supply and discharge pipes, m, 10, so that the water inthe tanks may be shut off from the hydraulic cylinder, D, when thepiston is to be packed or at other required times. In operating withthis apparatus, the pressure in the pressure discharge tank, M, ismaintained at the tension required to cause the pressure of the waterupon the piston during the discharge of the water to counterbalance tothe required extent the weight of the elevator car; it being understoodthat a sufficient portion of the weight of the car must remainuncounterbalanced to cause the car to descend, so that the water isforced from the cylinder D into the pressure discharge tank M. Thepressure of the air in the pressure supply tank H, on the other hand,should be sufiicient to raise the car with its load at the requiredspeed; such pressure being varied as usual in different elevators tosuit the area of the cylinder, the stroke of the piston and the maximumweight to be raised. By adjusting the pressure in the closed pressuredischarge tank, operating upon the piston of the hydraulic cylinderduring the descent of the car, the efiect of the weight of the car maybe opposed or counterbalanced to any desirable extent without the use ofa counterpoise weight. The force exerted-by so much of the weight of thedescending car as is employed in forcing the discharging water into thepressure discharge tank is utilized, because the pump is supplied fromthe same pressure discharge tank with Water under pressure, andtherefore has to overcome only the difference of the pressures existingin the two closed tanks.

I claim as my invention The combination substantially as before setforth of the single acting hydraulic cylinder with its piston and valve,the closed pressure supply tank, the closed pressure discharge tank, andthe connecting pipe and reducing valve by which the said two tanks areconnected.

In witness whereof I have hereto set my hand.

WILLIAM WIIET'IEN RENWICK.

Witnesses:

W. L. CoULTER, J. G. DUNBAR.

